The present invention relates to a patient system and method for monitoring a physiological parameter of a patient.
In today's patient monitoring systems, one of the most important tasks is to monitor condition and/or status of a patient, and to alarm medical staff in case that one or more monitored physiological parameters of the patient exceed pre-defined upper and/or lower alarm limits. These alarm limits may either be set manually, e.g. by medical staff, or can be set automatically, e.g. at start of a measurement or on user request. Each alarm limit may be set as fixed limit and/or can be based upon one or more current values of the physiological parameter of the patient e.g. determined by the patient monitoring system.
Various methods for determining alarm limits are disclosed e.g. in U.S. Pat. No. 4,994,790,
U.S. Pat. No. 5,226,416, or EP-A-909551. Generally speaking, one or more limit values are determined based upon a starting value e.g. by adding or subtracting parameters specific offset values to or from these starting value, or by multiplying the starting value with a parameter specific factor.
When exceeding alarm limits, the patient monitoring system usually provides an acoustic signal for alerting the medical staff. However, it has been proved that erroneous alarming (i.e. unnecessary or faulty alarming) might lead to a situation wherein the medical staff simply switches off the acoustic alarming in order not to be bothered or confused by such kind of erroneous alarms. It is clear that such kind of situations have to be avoided since otherwise a patient's critical condition might not be noticed after alarms have been switched off.
A problem different from the erroneous alarming but which might lead to the same situation of switched off acoustic alarms, is the omnipresence of acoustic signals in particular from different patient monitoring systems. Particularly in intensive care environments with a plurality of different patient monitoring systems also for a plurality of different patients, it has been found that acoustic signals might be perceived as being disturbing for medical staff as well as for the patients. This in particular when there are several different acoustic signals at the same time. In such environments, it has been found that either the volume of acoustic signals will be reduced to a very low value, or the acoustic signals might even be switched off entirely, thus leading to the same situation as described above wherein a critical situation of a patient might not be noticed.
The problem has even become worse in recent years with the introduction of patient monitoring systems wherein a measuring signal indicative of a patient's physiological parameter is modulated on an acoustic signal. Examples for such measurement-modulated acoustic signals are: The modulation of a beep tone that is issued with every heart beat with the value of the oxygen saturation of a patient, and a whistling sound that is issued with every detected breath, modulated with the respiratory rate or something similar for an invasively measured blood pressure.
While on one hand such measurement-modulated acoustic signals provide useful information in a very intuitive way, clinical staff often feels disturbed by those acoustic signals, thus leading to the aforementioned situation of unnoticed critical situations as a result of switched off or volume-reduced acoustic signals.
It is therefore an object of the present invention to avoid situations wherein clinical staff feels disturbed by acoustic signals from patient monitoring systems.